Summary: The distribution of radioarsenic among the various products in the presence of oxygen has been determined in the following series of experiments : 1. 1 M ASCl3 in benzene has been activated with thermal neutrons, 2. 77GeCl4 has been kept in contact with benzene, and 3. 77GeCl4 has been kept in contact with benzene in the γ-field of a 60Co-unit, at two different gamma dose rates. The distribution of the products (labelled with 76As and 77As, respectively) was determined by high-voltage paper electrophoresis. The results show that: 1. the distribution of radioarsenic is not only dependent on the properties of the recoil fragment produced in the nuclear process, but also on the radiation-increased chemical reactivity of the organic environment, 2. both 77As formed in the (n, γ) reaction and 77As produced by β-decay give the same organic yield, however, some changes in the distribution of products are observed, 3. the formation of the products by the hot processes is due mainly to reaction of the recoil atom with a single medium molecule or with its fragmentation products.